<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="css/index-pc.css" media="screen and (min-width: 1200px)">
    <link rel="stylesheet" href="css/index-pad.css" media="screen and (max-width: 1199px)">
    <link rel="stylesheet" href="css/index-phone.css" media="screen and (max-width: 768px)">
</head>
<body>
<div></div>
<!--
在开发，如果需要同时设置电脑/平板/手机端的样式，那么需要将电脑端引入在最前面，然后平板端引入在电脑的后面，手机端引入在平板端的后面
-->
<!--
外链格式：<link rel="stylesheet" href="css/xxx.css" media="条件">
-->
</body>
</html>